The three general objectives of this project are: 1. Elucidation of the anemia of uremia in terms of the kinetics of red cell transport and metabolism, the effects of hemodialysis, and other extracellular influences. 2. Examination of the effects of mechanical stress on red cell structure and function. 3. Assessment of the interrelationship between anion and cation transport in red cells. The data which have been accumulated to date show that the permeability of red cells from uremic patients is not altered by a 4-6 hour hemodialysis procedure, and that red cell transport processes are not affected by this therapy. Moreover, the ability of red cells from uremic subjects to withstand subhemolytic shear stress forces is not impaired by hemodialysis. In other studies, we have found that bumetanide, like furosemide, completely inhibits ouabain-insensitive sodium-sodium exchange in normal red cells. Phloretin inhibits both ouabain-sensitive and ouabain-insensitive unidirectional sodium fluxes over a wide concentration range.